Platelet indices and glucose control in type 1 and type 2 diabetes mellitus: A case-control study.

BACKGROUND AND AIMS: The relationship between platelet indices and glucose control may differ in type 1 (T1DM) and type 2 (T2DM) diabetes. We aimed to investigate differences in mean platelet volume (MPV), platelet count, and platelet mass between patients with T1DM, T2DM, and healthy controls and to explore associations between these platelet indices and glucose control. METHODS AND RESULTS: A total of 691 T1DM and 459 T2DM patients and 943 control subjects (blood donors) were included. HbA1c was measured in all subjects with diabetes and 36 T1DM patients further underwent 24 h-continuous glucose monitoring to estimate short-term glucose control (glucose mean and standard deviation). Adjusting for age and sex, platelet count was higher and MPV lower in both T1DM and T2DM patients vs control subjects, while platelet mass (MPV × platelet count) resulted higher only in T2DM. Upon further adjustment for HbA1c, differences in platelet count and mass were respectively 19.5 × 109/L (95%CI: 9.8-29.3; p < 0.001) and 101 fL/nL (12-191; p = 0.027) comparing T2DM vs T1DM patients. MPV and platelet count were significantly and differently related in T2DM patients vs both T1DM and control subjects; this difference was maintained also accounting for HbA1c, age, and sex. Platelet mass and the volume-count relationship were significantly related to HbA1c only in T1DM patients. No associations were found between platelet indices and short-term glucose control. CONCLUSION: By accounting for confounders and glucose control, our data evidenced higher platelet mass and different volume-count kinetics in subjects with T2DM vs T1DM. Long-term glucose control seemed to influence platelet mass and the volume-count relationship only in T1DM subjects. These findings suggest different mechanisms behind platelet formation in T1DM and T2DM patients with long-term glycaemic control being more relevant in T1DM than T2DM.

Leiomyomatosis peritonealis disseminata: an additional case.

Leiomyomatosis peritonealis disseminata (PPD) is a rare smooth muscle tumour of women in the reproductive age. It is characterized by multiple small nodules on the peritoneal surface, mimicking a metastatic process. To date, about 100 cases have been reported in literature. The authors herein present an additional case consisting of multiple nodules located on the surface of the omentum, parietal peritoneum, as well as colon and rectum wall in a patient without signs of excess of estrogen, progesterone, or steroid hormones nor treated with hormones for any reason. The patient has been submitted to laparoscopic myomectomy few years ago. Microscopically, these nodules consisted of bundles of spindle-shaped smooth muscle cells (positive for smooth muscle actin, desmin, estrogen, and progesterone receptor). A brief review of the literature on the pathogenesis of the disease is also added.

Myxoid leiomyosarcoma of the uterus: a case report.

Only 30 cases of myxoid leiomyosarcomas (MLMS) have been reported to date. The authors describe a further case in a 66-year-old woman. The main differential diagnoses include: myxoid inflammatory myofibroblastic tumours, mixoid leiomyoma, and endometrial stromal tumours. Surgery remains the appropriate treatment. However, in spite of an aggressive surgical approach and local and systemic control, recurrences and metastasis are frequent.

Longitudinal trajectories of psychosocial functioning in patients with pre-existing mental disorders after one year of COVID-19 pandemic.

Aims of the present study were to prospectively assess psychosocial functioning trajectories during the COVID pandemic and the possible impact of sociodemographic variables, as well as of COVID-19 pandemic-related factors, on these trajectories, in a sample of patients with pre-existing severe mental disorders. Moreover, we aimed at identifying predictors of impairment in psychosocial functioning over a period of 9 months of COVID-19 pandemic. Patients were recruited during the 3rd wave of the COVID-19 pandemic (T0, March-April 2021) while strict containment measures were applied in Italy, and reassessed after 3 months (T1, June-July 2021), and after 6 months from T1 (T2- November-December 2021), during the 4th wave of COVID pandemic. A sample of 300 subject (out of the 527 subjects recruited at baseline) completed the T2 evaluation. Patients were assessed by: Work and Social Adjustment Scale (WSAS) for psychosocial functioning, Generalized Anxiety Disorder 7-Item (GAD-7) for anxiety symptoms, Patient Health Questionnaire-9 (PHQ-9) for depressive symptoms and the Impact of Events Scale-Revised, for post-traumatic symptoms. Cluster analyses identified 4 trajectories of functioning: the High, Stable Functioning group (N = 77), the Improvement Functioning group (N = 62), the Progressive Impairment group (N = 83) and the Persistent Severe Impairment group (N = 78) respectively. We found that predictors of higher WSAS score at T2 were higher WSAS score at T0 (B = 0.43, p < .001), PHQ scores at baseline >10 (B = 2.89, p < .05), while not living alone was found to be a protective factor (B = -2.5, p < .05). Results of the present study provides insights into the vulnerability of individuals with psychiatric disorders during times of crisis. Study findings can contribute to a better understanding of the specific needs of this population and inform interventions and support strategies.

Metformin improves endothelial function in type 1 diabetic subjects: a pilot, placebo-controlled randomized study.

AIMS: Several studies have investigated the effects of metformin treatment in patients with type 1 diabetes mellitus (T1DM). No study has hitherto examined its effects on endothelial function in these patients. In this study we sought to evaluate the effect of metformin on endothelial function in type 1 diabetic patients. METHODS: Forty-two uncomplicated T1DM patients were randomized in a placebo-controlled, double-blind, 6-month trial to treatment with either metformin or placebo. Glycometabolic and clinical parameters as well as flow-mediated dilation (FMD) and nitrate-mediated dilation (NMD) of the right brachial artery were measured at baseline and at the end of the study. Glycaemic variability (GV, calculated from continuous glucose monitoring data) and a biomarker of oxidative stress [urinary 8-iso-prostaglandin F2α (PGF2α)] were also assessed. RESULTS: Baseline data were similar in the two groups. Compared with placebo, metformin significantly reduced body weight [-2.27 kg (95% confidence interval: -3.99; -0.54); p = 0.012] whilst improved FMD [1.32% (0.30; 2.43); p = 0.013] and increased PGF2α [149 pg/mg creatinine (50; 248); p = 0.004]. Notably, the improvement of FMD did not correlate with the decrease of body weight (r(2) < 1%). NMD, haemoglobin A1c, GV, daily insulin dose and other parameters did not significantly change after the treatment comparing the two groups. CONCLUSIONS: Our pilot trial showed that, in uncomplicated type 1 diabetic subjects, metformin improved FMD and increased PGF2α, a marker of oxidative stress, irrespective of its effects on glycaemic control and body weight. Randomized, blinded clinical trials are needed to evaluate the benefits and risks of metformin added to insulin in type 1 diabetes.

Development of the Italian version of the knee injury and osteoarthritis outcome score for patients with knee injuries: cross-cultural adaptation, dimensionality, reliability, and validity.

OBJECTIVE: Translating, culturally adapting and validating an Italian version of the Knee injury and Osteoarthritis Outcome Score (KOOS-I) to allow its use with Italian-speaking patients with knee complaints. DESIGN: The KOOS-I was developed by means of forward-backward translation, a final review by an expert committee, and a test of the pre-final version to establish its correspondence with the original English version. The psychometric testing included analysis of dimensionality using item-scale correlation after correction for overlap, reliability by means of internal consistency (Cronbach's alpha) and test-retest reliability (Intraclass Correlation Coefficients), and construct validity using an a priori hypothesised Pearson correlations with a Numerical Rating Scale (NRS) and the Short-Form 36 Health Survey (SF-36). RESULTS: The questionnaire was administered to 224 subjects with knee injuries and proved to be acceptable. Hypothesised item-to-domain correlations were observed for all of the items. The questionnaire showed good internal consistency (0.782-0.977), and a high level of test-retest reliability (0.850-0.949). Construct validity was supported by the confirmation of the a priori hypothesised correlations. CONCLUSIONS: The KOOS outcome measure was successfully translated into Italian, and proved to have good psychometric properties that replicated the results of existing versions. Its use is recommended for clinical and research purposes in patients with knee injuries.

Directed vascular expression of the thromboxane A2 receptor results in intrauterine growth retardation.

Thromboxane (Tx) A2 is a platelet agonist, smooth muscle cell constrictor, and mitogen. Urinary Tx metabolite (Tx-M) excretion is increased in syndromes of platelet activation and early in both normal pregnancies and in pregnancy-induced hypertension. A further increment occurs in patients presenting with severe preeclampsia, in whom Tx-M correlates with other indices of disease severity. TxA2 exerts its effects through a membrane receptor (TP), of which two isoforms (alpha and beta; refs. 5,6) have been cloned. Overexpression of TP in the vasculature under the control of the pre-proendothelin-1 promoter results in a murine model of intrauterine growth retardation (IUGR), which is rescued by timed suppression of Tx synthesis with indomethacin. IUGR is commonly associated with maternal diabetes or cigarette smoking, both conditions associated with increased TxA2 biosynthesis.

Eosinophilic esophagitis: an Italian experience.

BACKGROUND: Eosinophilic esophagitis is an esophageal disorder characterized by esophageal and/or upper gastrointestinal tract symptoms, and by dense esophageal eosinophilia associated with a normal gastric and duodenal mucosa. Prevalently reported in children, eosinophilic esophagitis has recently been reported with increased frequency also in adults. AIMS: The purpose of this study was to report our experience with eosinophilic esophagitis in Italy, since there are only very few series of such patients in our country. PATIENTS AND METHODS: We retrospectively reviewed the histological data of consecutive patients with a diagnosis of esophagitis or reflux disease in the period September 2004-September 2008. Eosinophils were counted where they appeared most numerous in the biopsy, with a cutoff > 15 eosinophils in more than one high-power field as diagnostic of eosinophilic esophagitis. Patients were excluded if gastric or duodenal biopsies showed a prominent eosinophilic infiltrate. RESULTS: Twenty two patients (14 adults, 8 children, age range 2-59 years) were identified according to the above criteria. The average eosinophil count was 86/ high-power field (range 31-150), associated with other pathologic features (eosinophilic microabscesses eosinophil degranulation, basal zone hyperplasia, papillary elongation). The main clinical complaints were dysphagia, food impaction, and heartburn, and endoscopic findings consisted of mucosal thickening and inelasticity, longitudinal shearing, rings, and white specks, without difference between adults and children for both clinical and endoscopic variables. CONCLUSIONS: Eosinophilic esophagitis is not rare in Italy, and displays clinical, endoscopic, and pathologic features similar to those described in other countries.

[Anaesthesia without anaesthetist?]. / L'anesthésie sans anesthésiste?

The continuing decline in the number of anaesthetists-intensive care physicians means that certain operations need to be performed under the responsibility of urologists alone. These procedures can be performed perfectly safely in selected patients, provided the urologist is aware of the inherent risks of each local and regional anaesthesia or sedation technique.

Distinct roles of prostaglandin H synthases 1 and 2 in T-cell development.

Prostaglandin G and H synthases, or cyclooxygenases (COXs), catalyze the formation of prostaglandins (PGs). Whereas COX-1 is diffusely expressed in lymphoid cells in embryonic day 15.5 thymus, COX-2 expression is sparse, apparently limited to stromal cells. By contrast, COX-2 is predominant in a subset of medullary stromal cells in three- to five-week-old mice. The isozymes also differ in their contributions to lymphocyte development. Thus, experiments with selective COX-1 inhibitors in thymic lobes from normal and recombinase-activating gene-1 knockout mice support a role for this isoform in the transition from CD4(-)CD8(-) double-negative (DN) to CD4(+)CD8(+) double-positive (DP). Concordant data were obtained in COX-1 knockouts. Pharmacological inhibition and genetic deletion of COX-2, by contrast, support its role during early thymocyte proliferation and differentiation and, later, during maturation of the CD4 helper T-cell lineage. PGE2, but not other PGs, can rescue the effects of inhibition of either isoform, although it acts through distinct EP receptor subtypes. COX-dependent PG generation may represent a mechanism of thymic stromal support for T-cell development.

Fertility following solid organ transplantation.

Fertility is usually restored in women after solid organ transplantation, and successful pregnancies have been reported in female recipients of kidney, liver, heart, pancreas-liver, and lung transplants. However, women with solid organ allografts have higher incidence of pregnancy complications like hypertension, preeclampsia, preterm delivery. Hypertension appears to be dependent on the type of immunosuppressive agents. The influence of pregnancy on the risk of rejection is poorly known on the basis of available data. Rejection rate appears to be at least similar to the nonpregnant population. In some cases, such as in liver transplant pregnant women, even higher as compared to the nonpregnant population. Maintaining appropriate blood levels of immunosuppressive drugs is currently recommended. Malformation rate in the offsprings of transplanted women appears to not be increased; long-term follow- up of children born to allograft recipients is necessary to investigate possible developmental, immunological, or oncological disorders. We followed 70 pregnancies after kidney transplantation and nine after liver transplantation. All recipients were maintained on immunosuppressive therapy during pregnancy, except one mother who refused immunosuppression and experienced transplant rejection. Hypertension was the most frequent complication during pregnancy: in 23% of kidney transplantated mothers and in one out of nine liver transplant recipients. The only malformation observed in the newborns was the dislocation of the hip in the child of a kidney transplant recipient.

In Silico Modeling of the Antiplatelet Pharmacodynamics of Low-dose Aspirin in Health and Disease.

The influence of platelet turnover on cyclooxygenase (COX-1) inhibition by low-dose aspirin remains largely uncharacterized due to limited feasibility of studying aspirin pharmacodynamics in bone marrow precursors. We developed an in silico compartmental model describing the aspirin effects on COX-1 activity in a population of megakaryocytes (MK) and in peripheral platelets. Model parameters were inferred from the literature and calibrated using measurements of serum thromboxane B2 (sTXB2 ), as proxy of COX-1 activity in peripheral platelets, in 17 healthy subjects and 24 patients with essential thrombocythemia (ET). The model reproduced well the average time-course of sTXB2 inhibition in healthy (accuracy = 10.4%), the reduced inhibition of sTXB2 observed in ET, and the effect of different dosing regimens. In conclusion, the in silico model accurately describes COX-1 inactivation by low-dose aspirin in MK and platelets in different clinical settings, and might help personalize aspirin regimens in conditions of altered megakaryopoiesis.

Parotid metastasis of renal cell carcinoma, mimicking primary clear cell oncocytoma: report of a case and brief review of the literature.

Malignancies of the parotid gland are relatively uncommon, accounting for only 3-6% of all head and neck cancers. Most of them are primary neoplasms, metastases are uncommon. Renal cell carcinoma (RCC) represents 3% of adult malignancies, the clear cell type comprises up to 70% of all RCC. RCC has an unpredictable behavior and the unique potential to metastasize to nearly every organ in the body. Though not as frequent, metastatic RCC to the head and neck has been identified in the thyroid, salivary glands, skull base, sinuses, pharynx, tonsils, tongue, lip and skin. Metastasis to the parotid gland is very rare. Here, we report the case of a clear cell type RCC metastatic to the parotid gland and mimicking a primary clear cell oncocytoma. Differential diagnoses and a brief review of the literature are added.

On-pump Cardiac Surgery Enhances Platelet Renewal and Impairs Aspirin Pharmacodynamics: Effects of Improved Dosing Regimens.

On-pump cardiac surgery may trigger inflammation and accelerate platelet cyclooxygenase-1 renewal, thereby modifying low-dose aspirin pharmacodynamics. Thirty-seven patients on standard aspirin 100 mg once-daily were studied before surgery and randomized within 36 hours postsurgery to 100 mg once-daily, 100 mg twice-daily, or 200 mg once-daily for 90 days. On day 7 postsurgery, immature and mature platelets, platelet mass, thrombopoietin, glycocalicin, leukocytes, C-reactive protein, and interleukin-6 significantly increased. Interleukin-6 significantly correlated with immature platelets. At day 7, patients randomized to 100 mg once-daily showed a significant increase in serum thromboxane (TX)B2 within the 24-hour dosing interval and urinary TXA2 metabolite (TXM) excretion. Aspirin 100 mg twice-daily lowered serum TXB2 and prevented postsurgery TXM increase (P < 0.01), without affecting prostacyclin metabolite excretion. After cardiac surgery, shortening the dosing interval, but not doubling the once-daily dose, rescues the impaired antiplatelet effect of low-dose aspirin and prevents platelet activation associated with acute inflammation and enhanced platelet turnover.

Structural dynamics of the mitochondrial ADP/ATP carrier revealed by molecular dynamics simulation studies.

The mitochondrial adenosine diphosphate/adenosine triphosphate (ADP/ATP) carrier has been recently crystallized in complex with its specific inhibitor carboxyatractyloside (CATR). In the crystal structure, the six-transmembrane helix bundle that defines the nucleotide translocation pathway is closed on the matrix side due to sharp kinks in the odd-numbered helices. The closed conformation is further sealed by the loops protruding into the matrix that interact through an intricate network of charge-pairs. To gain insight into its structural dynamics we performed molecular dynamics (MD) simulation studies of the ADP/ATP carrier with and without its cocrystallized inhibitor. The two trajectories sampled a conformational space around two different configurations characterized by distinct salt-bridge networks with a significant shift from inter- to intrarepeat bonding on the matrix side in the absence of CATR. Analysis of the geometrical parameters defining the transmembrane helices showed that even-numbered helices can undergo a face rotation, whereas odd-numbered helices can undergo a change in the wobble angle with a conserved proline acting as molecular hinge. Our results provide new information on the dynamical properties of the ADP/ATP carrier and for the first time yield a detailed picture of a stable carrier conformation in absence of the inhibitor.

Incidence and prognostic significance of karyotype abnormalities in de novo primary myelodysplastic syndromes: a study on 331 patients from a single institution.

The impact of clinical parameters, International Prognostic Scoring System (IPSS) scores/cytogenetic categories, and some single cytogenetic defects on overall survival (OS) and time to myelodysplastic syndromes (MDS)/AML progression (progression-free interval (PFI)) was evaluated in 331 MDS patients. Statistical analysis demonstrated that OS and PFI were significantly affected by all these parameters. Since single 7q- showed a better survival than the poor IPSS cytogenetic category (P=0.009), it was considered as a new prognostic entity ('modified IPSS categories'). In multivariate analysis OS was significantly influenced by age, marrow blast cell percentage, number of cytopenias and either modified or standard IPSS cytogenetic categories; hazard ratios for MDS/AML progression were influenced by all the former, except for age and cytopenias. Multivariate analysis of del(7)(q31q35) confirmed the results of univariate analysis, but the Akaike Information Criterion showed no difference in evaluating OS and PFI between the modified and standard IPSS cytogenetic grouping. In conclusion, (i) chromosome defects as grouped by IPSS and blast cell percentage are the most relevant parameters for predicting OS and PFI; (ii) the prognostic power of the IPSS cytogenetic grouping is not ameliorated by the introduction of del(7)(q31q35) as a new entity; (iii) complex karyotypes have a prognostic value independent of blast cell percentage.

Group-based task-oriented exercises aimed at managing kinesiophobia improved disability in chronic low back pain.

BACKGROUND: There are still doubts concerning the clinical impact of multidisciplinary cognitive behavioural rehabilitation programmes conducted in group-based settings and about their long-term effects on subjects with chronic low back pain (CLBP). This randomized, parallel-group superiority-controlled trial aimed at evaluating the effect of such a programme on disability, kinesiophobia, catastrophizing, pain and quality of life in CLBP. METHODS: One hundred and fifty patients were randomly assigned to a 5-week group-based multidisciplinary programme of task-oriented exercises integrated with cognitive behavioural therapy mainly aimed at managing kinesiophobia (experimental group, 75 subjects) or group-based traditional exercises (control group, 75 subjects). Before treatment, 5 weeks later (post-treatment), 12 and 24 months after the end of treatment, the Oswestry Disability Index, the Tampa Scale for Kinesiophobia, the Pain Catastrophizing Scale, a pain Numerical Rating Scale and the Short Form Health Survey were assessed. A linear mixed model for repeated measures was used for each outcome measure. RESULTS: Significant group (p < 0.001), time (p < 0.001) and time-by-group interaction (p < 0.001) effects were found on disability, with a between-group difference (95% confidence interval) after training in favour of the experimental group of -10 (-12; -8). Also kinesiophobia, catastrophizing, pain, and quality of life improved to a significantly greater extent in the experimental group. The improvements of the experimental group were maintained at follow-ups. CONCLUSION: This light group-based multidisciplinary cognitive behavioural rehabilitation programme was superior to traditional exercises in reducing disability, kinesiophobia, catastrophizing, and enhancing the quality of life of subjects with CLBP. The effects lasted for at least 2 years after the end of the intervention.

Cardiovascular responses to the isoprostanes iPF(2alpha)-III and iPE(2)-III are mediated via the thromboxane A(2) receptor in vivo.

BACKGROUND: Isoprostanes (iPs) are free radical-catalyzed products of arachidonic acid that reflect lipid peroxidation in vivo. Several iPs exert biological effects in vitro and may contribute to the functional consequences of oxidant stress. For example, iPF(2alpha)-III (8-iso PGF(2alpha)) and iPE(2)-III modulate platelet function and vascular tone. Although these effects are blocked by antagonists of the receptor (TP) for the cyclooxygenase product thromboxane A(2), it has been speculated that the iPs may activate a receptor related to, but distinct from, the TP. METHODS AND RESULTS: Transgenic mice (TPOEs) were generated in which the TP-beta isoform was under the control of the preproendothelin promoter. They overexpressed TP-beta in the vasculature but not in platelets and exhibited an exaggerated pressor response to infused iPF(2alpha)-III compared with wild-type mice. This was blocked by TP antagonism. The platelet response to the iP was unaltered in TPOEs compared with wild-type mice. By contrast, both the pressor response to iPF(2alpha)-III and its effects on platelet function were abolished in mice lacking the TP gene. This was also true of the effects of infused iPE(2)-III on mean arterial pressure and platelet aggregation. CONCLUSIONS: Both iPF(2alpha)-III and iPE(2)-III exert their effects on platelet function and vascular tone in vivo by acting as incidental ligands at membrane TPs rather than via a distinct iP receptor. Activation of TPs by iPs may be of importance in syndromes in which cyclooxygenase activation and oxidant stress coincide, such as in atherosclerosis and reperfusion after tissue ischemia.

Determinants of the interindividual variability in response to antiplatelet drugs.

The aim of this review article is to discuss the main determinants of the interindividual variability in response to antiplatelet agents. The main sources of pharmacokinetic and pharmacodynamic variability are reviewed, with particular emphasis on aspirin and clopidogrel. The term 'resistance' is uninformative of the mechanism(s) underlying interindividual variability in response to these antiplatelet agents, and is potentially misleading. Increased awareness of the distinct factors potentially interfering with the desired antiplatelet effects of aspirin or clopidogrel, particularly avoidable drug interactions, may ultimately result in better patient management than requesting unnecessary costly tests of platelet function. Similarly, new studies addressing the interindividual variability in response to these antiplatelet agents should rely upon mechanism-based biochemical end-points rather than platelet aggregation measurements. As with any drug used to prevent atherothrombosis, treatment 'failure' can occur with aspirin or clopidogrel perhaps not surprisingly, given the multifactorial nature of atherothrombosis. There is no scientific basis for changing antiplatelet therapy in the face of a treatment 'failure', as we cannot be sure whether a second vascular event occurring in the same patient will reflect the same pathophysiological event that led to the first. Moreover, we have no controlled evidence that changing therapy is a more effective strategy than maintaining an evidence-based therapy.

Active-site copper and zinc ions modulate the quaternary structure of prokaryotic Cu,Zn superoxide dismutase.

The influence of the constitutive metal ions on the equilibrium properties of dimeric Photobacterium leiognathi Cu,Zn superoxide dismutase has been studied for the wild-type and for two mutant protein forms bearing a negative charge in the amino acid clusters at the dimer association interface. Depletion of copper and zinc dissociates the two mutant proteins into monomers, which reassemble toward the dimeric state upon addition of stoichiometric amounts of zinc. Pressure-dependent dissociation is observed for the copper-depleted wild-type and mutated enzymes, as monitored by the fluorescence shift of a unique tryptophan residue located at the subunit association interface. The spectral shift occurs slowly, reaching a plateau after 15-20 minutes, and is fully reversible. The recovery of the original fluorescence properties, after decompression, is fast (less than four minutes), suggesting that the isolated subunit has a relatively stable structure, and excluding the presence of stable intermediates during the dimer-monomer transition. The dimer dissociation process is still incomplete at 6.5 kbar for the copper-depleted wild-type and mutated enzymes, at variance with what is generally observed for oligomeric proteins that dissociate below 3 kbar. Measurement of the degree of dissociation, at two different protein concentrations, allows us to calculate the standard volume variation upon association, Delta V, and the dissociation constant K(d0), at atmospheric pressure, (25 ml/mol and 3 x 10(-7)M, respectively). The holoprotein is fully dimeric even at 6.5 kbar, which allows us to evaluate a lower Delta G degrees limit of 11.5 kcal/mol, corresponding to a dissociation constant K(d0)<10(-9)M.